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Monthly Archives: February 2010
reblog: finding things that are inside other things
My post diary of a geonumpty to my main blog is really what got me started thinking about abstract geographic data. In it, I (with a lot of external help) develop queries to count points in areas with the same … Continue reading
making trivial shapefiles with shapelib
While most GIS applications work with delimited text inputs, sometimes you just have to have a shapefile. Amongst many other things, Frank Warmerdam wrote the Shapefile C Library, which comes with a few simple tools. I suspect Frank meant the … Continue reading
tale of two cities: coordinate reference systems, and what on earth is the maywood tot lot?
For reasons that are not particularly clear, the Toronto.ca|Open data is in two different coordinate reference systems (CRS), MTM 3 Degree Zone 10, NAD27 (EPSG 2019) and UTM 6 Degree Zone 17N NAD27 (EPSG 26717). This confuses QGIS even if … Continue reading
my first real spatial query: finding nearby libraries
Me and Catherine are quite partial to libraries. I’m going to use the address points database we made yesterday to find the libraries within 2km of a given address. It’s not a very useful query, but it shows the very … Continue reading
a simple geocoder for toronto
I’m going to use SpatiaLite and the Toronto One Address Repository to try some simple geocoding. That is, given an address, spit out the real-world map coordinates. As it happens, the way the Toronto data is structured it doesn’t really … Continue reading
free geodata for the numpty-about-Toronto
So if I want to learn some GIS skills, it would be helpful if I had some data to work with. Here are two data sources I have slight familiarity with: toronto.ca | Open Shapefiles, comprising: Municipal Address Points – … Continue reading
where am i?
My GPS just told me that the middle of the nearest road intersection to my house has the following coordinates: lat=43.73066, lon=-79.26482 What does that mean? Since latitudes are positive north from the equator, and longitudes positive east of the … Continue reading
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